Browsed byCategory: Research and Development

The SDR hardware sold online usually includes an antenna. These antenna are not suitable to pickup radio transmissions that are low powered or distant. Here is an example of NOAA weather radio that is transmitted about 15 miles from my location. This first image is with the standard antenna shipped with the SDR adapter. The signal noise ratio is narrow, meaning the noise floor is high and the signal ceiling is low. The audio is noisy and hard to hear….

Recently, someone I know purchased a network printer that was the same make and model as mine. They weren’t sure on how to setup the printer and asked for my help. The setup is not difficult, however the default settings leaves the printer open on its wireless interface. So there are more steps that are required to secure it. The challange facing us was distance, they live in another state. However, I was able to export my printer settings, which…

I saw these two videos about the Voyager spacecraft and the Golden Plate each of them contain and found they fit with the other material posted here. “That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every…

A large part of phone automation uses DTMF signaling. DTMF stands for Dual Tone Multi Frequency and has been in place since the 1960s. Dialing a phone number before the advent of DTMF involved using a rotor. The spinning dial would generate a number of pulses that the phone company would interpret as a number. The phone company then placed each number in order and after a set number was reached, the phone company would place the call. We still…

In my earlier post I discussed installing the ESPurna firmware on the ESP-01 module, a ESP8266 based IoT device. The firmware provides a Web as well as a telnet UI. In this post we’ll be more focused on the CLI via telnet. More specifically, we’ll be looking at the wifi.scan command issued in a telnet session to determine wireless coverage. The ESP-01 module is well suited for tasks like determining wifi coverage. It is small, can operate on a small…

The Tonbux power strip is an IoT device that allows control of each power outlet from a mobile device. These are sold on Amazon for around $30 each. It has a closed firmware that does not allow direct access to the power strip. Instead, a mobile device app must be installed and control is done through the app. From the looks of it, the power strip publishes with MQTT to a cloud based broker. In turn the mobile device app…

In this post we’ll cover how to monitor inexpensive wireless security sensors. There are two types of wireless sensors that we’ll be working with, door reed switches and passive infra red motion detectors. Each of these sensors transmit a broadcast radio message on the 433Mhz frequency. We’ll be expanding on earlier work with RTL_433. This post will cover how to identify a specific sensor and take appropriate action as needed, all that with a single bash script, let’s begin. The…

This post will cover how to monitor a Acurite temperature and humidity sensor with RTL_433 and a SDR dongle. Values from the sensor will be collected using a shell script and the results will be graphed in Cacti. Let’s begin. The Acurite sensor used is model number 06002M and it is the indoor outdoor sensor. It can be found on Amazon and currently lists for $13 each, http://a.co/d/fPybnET. It is powered by 2 AA batteries. The manufacturer suggests using Lithium…

In this post I’ll be covering how to use SDR on Linux to capture data from wireless sensors using Benjamin Larrson’s RTL_433. I’ll start by covering the required install steps followed by some rudimentary examples. First you will need some kind of USB SDR hardware, this example we will be using the NooElec Nano. Here are the steps to install the RTL_433 software. Open a terminal window and enter in the following commands. sudo apt-get install libtool libusb-1.0.0-dev librtlsdr-dev rtl-sdr…

There are plenty of examples online (https://learn.adafruit.com/getting-started-with-rtl-sdr-and-sdr-sharp/overview) on how to receive images from NOAA satellites using SDR. This post will be about my experiences and ideas on how to improve the process I used. There are several items needed before having a finished image. These were the pieces used in my setup and some description about each. The first is the SDR hardware. Obviously this will be a requirement. It’s the typical DVB-T USB device most commonly used for SDR….